Electromagnetic Pump

ABSTRACT

The invention relates to an electromagnetic pump comprising precisely one coil, wherein the one coil has a longitudinal axis, a ferromagnetic first core section at least partially arranged in the one coil, a ferromagnetic second core section at least partially arranged in the one coil, and a ferromagnetic armature, wherein a primary air gap is arranged between the armature and the first core section, wherein a radial secondary air gap is arranged between an insertion section of the armature and a receiving section of the second core section facing the longitudinal axis, wherein the ferromagnetic armature has a truncated cone-shaped contour narrowing in the stroke direction in a front section facing the first core section, wherein a magnetic force between the armature and the first core section is greater in a closing process of the first air gap; than a magnetic force between the armature and the second core section.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation patent application claiming priority to PCT Application number PCT/EP2013/001850 filed on Jun. 24, 2013, which claims priority to German Patent Application number DE10 2012 012 779.0 filed Jun. 25, 2012 and is hereby incorporated in its entirety.

FIELD

The invention relates to an electromagnetic pump.

BACKGROUND

Electromagnetic pumps known from practice comprise a coil which extends along a longitudinal axis, the coil being penetrated by in part in each case by a first ferromagnetic core part and a second ferromagnetic core part. The ferromagnetic core parts are spaced apart from one another in the interior of the coil, an armature which penetrates the two core parts at least in part being displaced as a result of the resultant magnetic field when the coil is excited. In this case, an axial primary air gap is arranged between the first ferromagnetic core part and the armature and a radial secondary air gap is arranged between the second ferromagnetic core part and the armature, an insertion portion of the armature which is guided in the second core part being developed in a cylindrical manner. The cylindrical insertion portion, in this case, is received in an equally cylindrical receiving portion of the second core part, a bevel which facilitates the insertion of the armature being able to be provided in the region of the end face of the receiving portion which faces the first core part. In a disadvantageous manner, however, as a result of the cylindrical development of the insertion portion, the structural design of the magnetic circuit is limited substantially to the first ferromagnetic core part and the armature head of the armature which faces the first ferromagnetic core part. In an additionally disadvantageous manner, the movement of the armature toward the end of the exciting of the coil has to be controlled by a costly electronics system for braking in order to obtain a stroke-force characteristic which deviates from a substantially exponentially increasing stroke-force characteristic.

DE 10 2008 058 046 A1 describes in an exemplary embodiment an electromagnetic reciprocating pump with a coil and a first ferromagnetic core part and a second ferromagnetic core part that are arranged in portions in the coil. A ferromagnetic armature is received in a support sleeve that is produced from a material that is not magnetically conducting, the support sleeve being provided in a receiving portion of the second core part which faces the first core part. A primary air gap is arranged between the armature and the first core part and a secondary air gap is arranged between an insertion portion of the armature and a receiving portion of the second core part. On an end that faces the first core part, the magnetic armature comprises a recess in which is received a first spring which is supported on the first core part at its end that is remote from the armature. A supporting element, on which a first end of a second spring is supported, is provided on an end of the armature that faces the second core part. A second end of the second spring is supported on a recess of a dosing cylinder which is received in the second core part. When the coil is excited, the armature is displaced in the direction of the first core part as a result of a magnetic force in opposition to a spring force of the first spring, the primary air gap being closed. In this connection, a magnetic force between the armature and the first core part is greater than a magnetic force between the armature and the second core part. The insertion portion and the receiving portion do not comprise any conical portions by means of which a stroke-force characteristic that alters over the stroke is able to be realized. In order to deviate from a substantially exponentially increasing development of the stroke-force characteristic, additional measures such as, for example, the provision of control electronics, have to be taken.

US 2009/0 200 499 A1 shows an electromagnetic linear drive for a pump with a coil which is enclosed in portions by a first ferromagnetic core part and a second ferromagnetic core part. A ferromagnetic armature with yoke portions and magnetic portions is accommodated so as to be displaceable in a central region of the first core part and of the second core part. The armature comprises a first guide portion and a second guide portion, by way of which the armature is guided in a first centering disk and a second centering disk. An air gap is realized between the armature and the first core part as well as between the armature and the second core part. However, no primary air gap is arranged between the armature and the first core part. Thus, no magnetic force is produced either between the armature and the first core part which, during a closing operation of the first air gap, being greater than a magnetic force between the armature and the second core part. Finally, no insertion portion with at least one conical portion which comprises an opening angle that deviates from the truncated-cone-shaped contour of the front region of the ferromagnetic armature is provided either.

DE 11 01 960 B describes an electromagnetic pump, including a coil which is enclosed by a ferromagnetic housing. The housing forms a cylindrical pump chamber in which a ferromagnetic core part is received. A ferromagnetic armature is additionally received in the pump chamber so as to be axially displaceable, an air gap being formed between the armature and the core part. The pump chamber is defined on an end that is located opposite the core part by a closing flange which is produced from a material that is not magnetically conducting. The armature is biased in relation to the closing flange by means of a spring which is supported on the core part and the armature, an abutment being formed on the armature by a radially protruding insertion portion of the armature, by way of which the armature is guided in the pump chamber. When the coil is excited, the armature is displaced in the direction of the core part as a result of a magnetic force in opposition to a spring force. Once the coil has been de-excited, the armature passes back into a biased starting position. According to an exemplary embodiment, the armature can also comprise a conical shape. A second core part that is arranged at least in part in the coil is not provided, neither is a second core part that is arranged at least in part in the coil. A radial secondary air gap between the insertion portion of the armature and the receiving portion of the second core part is missing such that, during a operation closing the first air gap, a magnetic force between the armature and the first core part is greater than a magnetic force between the armature and the second core part. Finally, no insertion portion with at least one conical portion which comprises an opening angle that deviates from the truncated-cone-shaped contour of the front region of the ferromagnetic armature is provided either.

DD 128 346 A1 shows an electromagnetic drive with a coil and a first ferromagnetic core part. A ferromagnetic armature with an insertion portion is received so as to be displaceable in a receiving portion of a second ferromagnetic core part. A primary air gap and a secondary air gap are arranged between the armature and the first core part as well as between the armature and the second magnetic core part. When the coil is excited, a magnetic force between the armature and the first core part is greater than between the armature and the second core part, as a result of which the armature is displaced in the direction of the first core part and the primary air gap is closed. The insertion portion of the armature comprises a stepped contour. A ferromagnetic armature with a front region that faces the first core part and has a truncated-cone-shaped contour that tapers in the stroke direction is not shown. A front region of the armature, which protrudes radially beyond an end face of the receiving portion of the second core part facing the first core part, and an insertion portion with at least one conical portion which comprises an opening angle that deviates from the truncated-cone-shaped contour of the front region of the ferromagnetic armature, are not shown.

DE 696 07 230 T2 describes an electromagnetic pump, including a coil and a first ferromagnetic core part. A second ferromagnetic core part is arranged opposite the first core part, the first core part and the second core part forming a low pressure chamber of the pump. A ferromagnetic armature is received so as to be displaceable in the low pressure chamber. A primary air gap is arranged between the armature and the first core part and a secondary air gap is arranged between the armature and the second core part. The armature comprises a receiving portion on which a first end of a spring is supported. A second end of the spring is supported on a continuation of a housing part of the pump that defines the low pressure chamber. As a result, the armature is pre-stressed in relation to a spacer of the second core part. When the coil is excited, a magnetic force between the armature and the first core part is greater than between the armature and the second core part, as a result of which the armature is displaced in the direction of the first core part in opposition to a spring force. In this connection, the primary air gap between the armature and the first core part is reduced. In a de-excited state of the coil, the armature passes back into a starting position as a result of the spring force. The contour of the armature comprises cylindrical portions with different diameters and conical portions. A ferromagnetic armature with a front region that faces the first core part with a truncated-cone-shaped contour that tapers in the stroke direction or a front region of the armature which protrudes radially beyond an end face of the receiving portion of the second core part facing the first core part is not shown. Finally, an insertion portion with at least one conical portion which comprises an opening angle that deviates from the truncated-cone-shaped contour of the front region of the ferromagnetic armature is not provided.

U.S. Pat. No. 2,006,592 A shows an electromagnetic pump, including a first coil and a second coil which are arranged spaced apart axially from one another in a pump housing. The first coil and the second coil are defined on the inside in a radial manner by a support sleeve which is produced from a material that is not magnetically conducting and forms a pump chamber of the pump. The pump chamber is defined at one end in the axial direction by a first ferromagnetic core part which is enclosed in part by the second coil. At the other end, the pump chamber is defined in the axial direction by a second ferromagnetic core part which is enclosed in part by the first coil. A ferromagnetic armature is received in the pump chamber so as to be axially displaceable. When the coil is excited, the armature is displaced in the direction of the first core part as a result of a magnetic force, the primary air gap being closed. When the first coil is de-excited and the second coil excited, the armature is displaced in the direction of the second core part as a result of a magnetic force acting in the opposite direction, the secondary air gap being closed. The armature, on a first end and a second end, comprises conical insertion portions which are aligned with conical receiving portions in the first core part and the second core part such that the armature is guidable into the first core part and the second core part. An electromagnetic pump with precisely one coil is not shown. Neither is a radial, secondary air gap arranged between the insertion portion of the armature and the receiving portion of the second core part that faces to the longitudinal axis. An insertion portion with at least one conical portion which comprises an opening angle that deviates from the truncated-cone-shaped contour of the front region of the ferromagnetic armature is not shown either.

FR 2 428 343 A1 describes an electromagnetic linear drive with a coil that is arranged in a housing. The coil is received in a clamping manner between a first housing half and a second housing half and projects into an actuator chamber. A U-shaped ferromagnetic core part is arranged around the coil. A ferromagnetic armature penetrates the coil and the core part and is received so as to be displaceable in the first housing half by means of a first cylindrical guide portion in the second housing half and by means of a second cylindrical guide portion. The second guide portion is enclosed by a spring which is supported at the one end on the second housing half and at the other end on a spring plate that is fixed on the armature such that the armature is biased in relation to the second housing half. When the coil is excited, the armature is displaced in the direction of the second housing half as a result of a magnetic force in opposition to a bias. With the coil de-excited, the armature passes back into a starting position on account of the resetting action of the spring. The armature is realized in a conical manner along a portion that is located in the core part and the coil.

It is the object of the invention to provide an electromagnetic pump which enables a favorable stroke-force characteristic.

This object is achieved according to the invention by an electromagnetic pump with the features of claim 1.

According to the invention, an electromagnetic pump includes a coil which comprises a longitudinal axis, a first ferromagnetic core part which is arranged at least in part in the coil and a second ferromagnetic core part which is arranged at least in part in the coil as well as a ferromagnetic armature. A magnetic field which extends over the two core parts and the armature is generated when the coil is excited. In this case, the magnetic field has to bridge a primary air gap between the armature and the first core part and a secondary air gap between an insertion portion of the armature and a receiving portion of the second core part that is turned to the longitudinal axis, where a magnetic force acting between the armature and the first core part during a closing operation is always greater than a magnetic force between the armature and the second core part.

At least one of insertion portion of the armature and receiving portion of the second core part comprise a contour which deviates from a cylindrical form. The deviating contour is itself preferably cylindrical e.g. realized as a radial ring or radial groove. In an advantageous manner, in this way, as a result of simple modification to the geometry of the insertion portion of the armature and/or to the receiving portion of the second core part, different characteristics can be realized in one product family corresponding to a requirement.

Preferably, the stroke-force characteristic and/or the stroke-force development comprises a force as strong as possible at the start of a stroke movement, where, in contrast, in a middle stroke region only an average force is generated which clearly reduces toward the end of the stroke.

As a result of the geometric modifications, the magnetic resistance at the secondary air gap is strongly stroke-dependent and is, compared to the primary resistance, greater than in the case of known lifting magnets. As a result of developing the deviating contour in a corresponding manner, a stroke force of the ferromagnetic armature can be matched to a respective movement portion of the armature.

The electromagnetic pump makes it possible, as a result of modifications to the geometry of the pump parts that define the secondary air gap, to influence, in particular to increase or to reduce, the force by means of the forward movement of the armature obtained as a result of exciting the coil, and to modify same over the stroke path of the armature. Accordingly, it is possible in particular, as a result of modifying the secondary air gap in the region of the last part of the stroke of the armature, to influence the force such that the armature is not displaced at maximum force, but experiences braking and consequently the material of the pump is subject to less wear and tear. As a result, expensive electronic reduction of the exciting of the coil can be avoided and simple, cost-efficient activation can be provided. In addition, the service life of the electromagnetic pump is extended and the mechanical demands on the corresponding parts of the pump are reduced.

According to a first preferred development of the electromagnetic pump, it is provided that at least one of insertion portion of the armature and receiving portion of the second core part comprises a contour that deviates from the cylindrical shape over a region of at least one sixth, preferably one quarter of a maximum axial extension of the secondary air gap.

In an expedient manner, the region, in which the contour of the insertion portion or of the receiving portion that deviates from the cylindrical contour is provided, is provided at a spacing from the end face of the second core part that faces the first core part. For example, the contour that deviates from the cylindrical contour can be formed by a step in the region of the receiving portion or of the insertion portion, it also being possible for several steps to be provided. It is possible, in particular, for the region that deviates from the cylindrical contour of the periphery of the insertion portion itself also, in turn, to comprise a cylindrical peripheral portion, the spacing to the axis of the armature of which, however, deviating from that of the periphery of the insertion portion. It is possible for the corresponding region to consist of several part steps, said part steps preferably being realized in a rotationally symmetrical manner. However, it is also possible to provide developments that deviate from the rotational symmetry. A constriction can preferably be provided on an end of the receiving region of the second core part facing the first core part. As a result, the magnetic resistance is advantageously reduced in an end region of the stroke movement of the armature such that a powerful fluid emission can be obtained. However, in an advantageous manner, a constriction can also be provided on an end of the receiving region of the second core part that is remote from the first core part. As a result, the magnetic resistance is advantageously increased in the end region of the stroke movement of the armature such that the stroke movement is advantageously braked prior to the armature contacting the first core part.

In an expedient manner, both the insertion portion and the receiving portion are provided with a region which deviates from the cylindrical contour and preferably, but not necessarily, is overlapped in part such that, as a result of the stroke of the actuator, the configuration of the secondary air gap is influenced over at least one sixth, preferably one quarter of the maximum extension of the secondary air gap, which the same assumes in the de-excited state of the coil. Thus, for example, it can be provided that a region that is recessed in relation to the periphery of the insertion portion is provided in such a manner on the insertion portion that said region is arranged in such a manner on the receiving portion with a region that is also recessed that the insertion portion and the receiving portion, when a certain stroke of the actuator is reached, coincide and consequently influence said phase of the stroke in a particular manner. The same can be provided for the start phase of the stroke. In a particularly preferred manner, the recessed region of the receiving portion forms a constriction on an end of the receiving portion that faces the first core part and the recessed region of the insertion portion forms a flange on an end of the armature that is remote from the first core part. In this case, this results in an advantageous manner in a strong reduction in the magnetic resistance in an end region of the stroke movement of the armature.

According to a preferred further development, it is provided that at least one of insertion portion of the armature and receiving portion of the second core part comprises a contour that deviates from the cylindrical contour over a region of at least one third of a maximum axial extension of the secondary air gap. In an expedient manner, that region of the maximum axial extension of the secondary air gap over which the insertion portion and/or the receiving portion deviate from a cylindrical contour makes up more than half, in a particularly preferred manner more than three quarters of the corresponding extension such that the effect occurring when the armature is displaced is particularly marked. It is preferably to be provided in particular that both the insertion portion and the receiving portion deviate from the cylindrical shape in order to influence the secondary air gap in a particularly effective manner as a result. The deviating contour preferably extends over several and/or larger regions, in a particularly preferred manner at least two contour portions that deviate from the cylindrical contour and are spaced apart from one another being provided. An electromagnetic pump, which comprises improved magnetic flux conductance at precisely definable moments of the movement of the armature, is created advantageously as a result.

According to a second preferred development of the electromagnetic pump, it is provided that at least one of insertion portion of the armature and receiving portion of the second core part is realized in a conical manner over a region of at least one sixth, preferably one quarter of a maximum extension of the secondary air gap. As an alternative to this, a parabolic, elliptical or hyperbolic realization of the insertion portion of the armature or of the receiving portion of the second core part can be provided in place of the conical realization or in combination with the conical realization. As a result of choosing the form of the insertion portion or of the receiving portion in a suitable manner, a pump that is adapted to a specific situation can be created. In an expedient manner, the correspondingly realized insertion portion or receiving portion extends over more than half of the axial extension of the corresponding parts, in particular over the entire axial extension in the region of the secondary air gap. This can be produced in a simple manner from a manufacturing point of view by the receiving portion in total, or in any case over the region which accepts the insertion portion of the armature, experiencing a slightly conical development which only deviates, however, from the cylindrical shape by a few degrees. In an expedient manner, but not necessarily, the insertion portion of the armature is realized at the same cone angle such that when the coil is de-excited, the outside cone of the insertion portion has the greatest proximity to the inside cone of the receiving portion. As the coil is excited, the width of the secondary air gap increases, and in a corresponding manner the force is reduced as the stroke of the armature increases. As an alternative to this, it is possible to increase the force as the stroke increases by reversing the orientation of the inside cone and the outside cone. It has to be understood that the portions which are realized in a conical manner, can also be spaced apart from one another with cylindrical steps, or, however, can be provided only in regions of the periphery of the portion.

According to a third preferred development of the electromagnetic pump, it is provided that precisely one of insertion portion of the armature and receiving portion of the second core part comprises a stepping with a widened secondary air gap. As a result, in an effective manner it is only necessary to machine one of the two parts, insertion portion of the armature and receiving portion of the second core part, to the effect that it comprises a stepping with a widened secondary air gap, for example by a recess, which forms a prismatic or a rounded ring groove, being provided on the insertion portion of the armature, or where a recessed and expediently circumferential ring groove is provided in the region of the receiving portion. In particular when the insertion portion of the armature is realized in a corresponding manner, this can be effected in a simple manner from a manufacturing point of view, and a correspondingly machined armature can be used in existing core parts. In addition, depending on the selection of the position of the stepping on the armature, a different characteristic can be set both with regard to the stroke and to the intensity of the modification of the force such that several different armatures can be inserted into the same core part in the manner of a modular system in each case adapted to the requirements of the specific pump. The solution achieved can be realized in a simple manner from a manufacturing point of view and consequently is able to be produced in a cost-efficient manner.

According to a further preferred development of the electromagnetic pump, it is provided that a projection that protrudes radially from the insertion portion of the armature comprises a face that faces the first core part. In an advantageous manner, when the coil is excited, a modified axial magnetic force onto the armature is made possible. The projection that protrudes radially in front of the insertion portion of the armature is expediently realized in a rotationally symmetrical manner such that it surrounds the insertion portion in the manner of a ring. In this connection, different cross sections of the projection are possible, for example as trapezes, triangles, rectangles, dovetails, large U's or the like. In addition, it is possible for more than one projection to be provided, for example with a cross section that is formed as a large W or several projections that are located one behind the other with different cross sections. The at least one projection comprises a face which faces the first core part, this means which has at least one component which points in the stroke direction of the armature when being excited. Said face, in the case of a particularly simple realization, is located in a plane that is normal to the stroke direction, however, it is also possible for said face to comprise an inclination in the manner of a truncated cone. In an expedient manner, the projection extends only over a longitudinal portion of the insertion portion of less than one sixth of the extension thereof and is provided at a point of the peripheral portion which, even at maximum stroke, is still spaced axially from the end face of the receiving portion that faces the first core part.

According to a further preferred development of the electromagnetic pump, it is provided that the receiving portion of the second core part comprises an inside projection which points to the longitudinal axis. As a result, the magnetic flux density in the pump increases such that a modified magnetic force is exerted onto the armature. The inside projection expediently comprises a face that faces the first core part, and where the design is symmetrical, also a face that faces away from the first core part.

If both the insertion portion of the armature comprises a protruding projection and the receiving portion of the second core part comprises an inside projection, as a result of the magnetic interaction between said two parts which approach one another or move away from one another over the stroke of the armature, it is possible to obtain force components which raise or lower the force of the armature over the stroke. Consequently, an axial force component, which can be realized easily as a result of selecting the position of the projection or of the inside projection, becomes effective in the region of the secondary air gap. The force components desired in each case are produced as a result of the suitable arrangement of the projection and the inside projection, that means whether the projection is displaced in the direction toward the inside projection or away from the inside projection. It has to be understood that overlapping effects are possible where more than one projection and/or more than one inside projection are provided. In an expedient manner, the inside projection and the projection overlap in part in axial projection. In this connection, the effective axial faces of the portions of the two projections located opposite axially are preferably clearly smaller than the axially opposite faces of the armature cone and armature counterpart; the ratio between the faces is preferably less than 1:10, in a particularly preferred manner less than 1:25.

According to a preferred further development of the electromagnetic pump, in the region of the secondary air gap the maximum outside diameter of the insertion portion of the armature is smaller than the minimum inside diameter of the receiving portion of the second core part. The achievement as a result is that the pump is advantageously simple to mount without a two-part or multiple-part development of one of the first or of the second core part being necessary as the armature can simply be inserted into the second core part without, for example, rotation of the second core part in relation to the armature or a two-part development of the second core part being required.

According to a preferred development, it is provided that the contour that deviates from a cylindrical shape comprises a plurality of steps. To this end, the plurality can be provided in the insertion portion of the armature and/or in the receiving portion of the second core part, as a result of which force progressions that can be adapted or influenced individually over the stroke are produced. By providing several axially offset contour portions, a sufficient overlapping face is advantageously achieved between the armature and the receiving portion even in the case of a small magnetic stroke, as they act in parallel for the magnetic resistance.

In a preferred further development, the insertion portion of the armature is moved, preferably fully, out of the receiving portion of the second core part. As a result, the magnetic resistance is increased, which in an advantageous manner achieves a braking of the movement of the armature at an end of the stroke movement, the strength at which the armature contacts the first core part at the end of the stroke movement being damped in an advantageous manner as a result.

A support sleeve produced from plastics material or the like can be provided as an extension of the receiving portion for guiding the armature. The support sleeve can also be provided for lining a recessed groove in the armature or receiving portion. In particular when the recessed groove is arranged in the region of the end face of the receiving portion out of which the insertion portion of the armature extends at least so far that only the groove still overlaps the insertion portion, the support sleeve brings about a centering of the insertion portion without impairing the magnetic force in a noticeable manner. To this end, the support sleeve is selected expediently from a material which is not magnetically conducting and consequently is to be equated magnetically in a substantial manner with an air gap. As an alternative to this, it is also possible to provide a material which comprises lower magnetic conductivity compared to the material of the receiving portion, as a result of which the magnetic resistance is adjustable in the region of the lining, e.g. a plastics material with embedded ferromagnetic particles. In particular, at the same time the support sleeve can line a region of the receiving portion that deviates from the cylindrical shape and lengthen the receiving portion. Thus, for example, a support sleeve produced from polytetrafluoroethylene can be attached to the end face of the receiving portion.

According to a preferred further development, it is provided that the front region of the armature protrudes radially beyond an end face of the receiving portion of the second core part that faces the first core part. It is, however, also possible for the front region of the armature to comprise a reduced outside diameter which does not protrude radially beyond the end face of the receiving portion that faces the first core part. As a result, the magnetic force in the region of the primary air gap is able to be dimensioned smaller and in a corresponding manner it does still overlap the magnetic force in the region of the secondary air gap as the axial component of the magnetic field clearly outweighs the radial component of the magnetic field. Nonetheless, a comparably gentle response characteristic of the armature to the excitation can consequently be achieved, above all when an oppositely directed axial component of the magnetic field influences in the region of the secondary air gap. As a result of adjusting the corresponding parameters, the stroke of the armature carried out, for example, can be linearized at least approximately by means of the current strength, as a result of which in a particularly favorable manner part strokes can also be set, for example using a pressure-regulating pump. In the case of a pressure-regulating pump, the spring force and, where applicable, the effective piston areas of the armature are matched such that the armature is not reset jerkily in opposition to the stroke direction and a certain volume is ejected, rather a pressure is adjusted in the outlet line.

An electromagnetic pump is preferably characterized in that the conical portion of the insertion portion of the armature tapers in opposition to the truncated-cone-shaped contour of the front region of the armature that tapers in the stroke direction, as a result of which an axial component, in particular which acts in opposition to the stroke direction, of the magnetic force that displaces the actuator is achieved.

In this connection, it is advantageously provided that the conical portion of the insertion portion of the armature extends in part outside the receiving portion.

The conical portion of the receiving portion that tapers in opposition to the stroke direction then preferably adjoins an end face of the second core part that faces the first core part.

In an expedient manner, the conical portion of the insertion portion of the armature that tapers in opposition to the stroke direction is steeper than the truncate-cone-shaped contour of the front region of the armature that tapers in the stroke direction.

A pump that can be mounted in a particularly simple manner is produced when the region of the receiving portion which is placed outside the conical portion of the receiving portion that tapers in opposition to the stroke direction and points in the pump direction is realized in a cylindrical manner. In particular when the region of the insertion portion that penetrates into the cylindrical region of the receiving portion is also realized in a cylindrical manner, both parts can easily mesh into one another.

The electromagnetic pump is selected in a preferred manner from the group comprising a reciprocating pump, a diaphragm pump, a pressure-regulating pump and a dosing pump.

Further advantages, characteristics and further development of the invention are produced from the following description of preferred exemplary embodiments as well as from the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a longitudinal section through an electromagnetic pump with a first preferred embodiment of a secondary air gap.

FIG. 2 shows an enlarged detail of the embodiment according to FIG. 1.

FIG. 3 shows a second embodiment of the secondary air gap with a conical gradient of the insertion portion.

FIG. 4 shows a third embodiment of the secondary air gap with a stepping of the insertion portion.

FIG. 5 shows a fourth embodiment of the secondary air gap with a conical gradient of the insertion portion and a complementary receiving portion.

FIG. 6 shows a fifth embodiment of the secondary air gap with a wavelike contour of the insertion portion.

FIGS. 7A-C show the movement progression of a sixth embodiment of the secondary air gap.

FIG. 8 shows a further embodiment of the secondary air gap with grooves in the insertion portion and receiving portion.

FIG. 9 shows a longitudinal section through an electromagnetic pump with a further preferred embodiment of a secondary air gap.

DETAILED DESCRIPTION

FIG. 1 shows an electromagnetic pump 100 which is realized as a dosing pump, having a housing 101, an electromagnetic coil 102 which is arranged in the housing 101, a first ferromagnetic core part 103 and a second ferromagnetic core part 104. The electromagnetic coil 102 is wound on a coil carrier 105 and in its inside region is penetrated in each in case in part by the first ferromagnetic core part 103 and the second ferromagnetic core part 104. The two ferromagnetic core parts 103, 104 are spaced apart from one another by a pump chamber 107 which defines a spacing 106, the first ferromagnetic core part 103 comprising a feed line 108 and the second ferromagnetic core part 104 comprising an outlet line 109 for a fluid to be conveyed. A movable, ferromagnetic armature 110 is arranged in the pump chamber 107, which armature 110 is biased into a conveying direction 112 of the electromagnetic pump 100 by means of a spring 111 which is arranged between the armature 110 and the first core part 103. The armature 110 comprises a substantially hollow-cylindrical form and is penetrated by a piston rod 113 in its entire longitudinal extension, the piston rod 113 projecting beyond the armature 110 in the conveying direction 112 and in this case penetrating a dosing cylinder 114. The armature 110 comprises in its front region 115 which faces the first core part 103 a truncated-cone-shaped contour that tapers in the stroke direction. The first core part 103 comprises a conical counterpart 119 which faces the armature 110 and is realized in a complementary manner to the front region 115 of the armature 110, a region between the armature 110 and the conical armature counterpart 119 being designated as a primary air gap. The front region 115 projects into the axial spacing between both core parts 103, 104. The armature 110 extends by way of an end, which is remote from the first core part 103 and is realized as an insertion portion 117, into a receiving portion 118 of the second core part 104, the front region 115 of the armature 110 protruding radially beyond an end face of the receiving portion 118 of the second core part 104 that faces the first core part 103. A region between the insertion portion 117 of the armature 110 and the receiving portion 118 of the second core part 104 is designated as a secondary air gap.

The region between the front region 115 of the armature 110 and the counterpart 119 of the first core part 103 defines a primary air gap 151, the axial extension thereof being the maximum when the coil 102 is de-excited. The peripheral face of the insertion portion 117 of the armature 110 and the receiving portion 118 of the second core part 104 that faces the longitudinal axis of the coil 102 define a substantially radial secondary air gap 152 in the region in which they are opposite one another. The longitudinal axis is designated as 153 in FIG. 1. When the coil 102 is excited, on account of the magnet field produced, the magnetic force between the armature 110 and the first core part 103 during a closing operation of the first air gap 151 is greater than the magnetic force between the armature 110 and the second core part 104.

When the coil 102 is excited, a magnetic field is generated inside the coil 102, the ferromagnetic armature 110 being acted upon by a magnetic force in opposition to the conveying direction 112 and being displaced. The magnetic force moves the armature 110 in the direction of the first core part 103 in opposition to the bias of the spring 111, the front region 115 of the armature 110 being pushed into the complementarily realized counterpart 119 of the first core part 103. The spring 111 is tensioned further at the same time. When the coil 102 is de-excited, the armature 110 is once again displaced in the conveying direction 112 as a result of the bias of the spring 111, and the piston rod 113 presses the fluid located in the dosing cylinder 114 downstream of a non-return valve 160.

FIG. 2 shows an enlarged detail of the pump 100 according to FIG. 1, from which, in particular, the precise development of the outside contour of the insertion portion 117 and of the receiving portion 118 is produced. In this connection, the insertion portion 117 of the armature 110 in the region of an otherwise cylindrical peripheral surface comprises a ring-shaped outside projection 120 which extends over the entire radial periphery of the insertion portion 117. Said radially protruding outside projection 120 at the same time provides the maximum outside diameter of the insertion portion 117 and comprises a radially outwardly pointing ring surface 120 a, which is concentric to the peripheral surface of the insertion portion 117 and is connected to the remaining insertion portion 117 by means of a first face 120 b which points in the stroke direction and consequently faces the first core part 103, and is connected to a rear region of the insertion portion 117 by means of a second face 120 c which is remote from the first core part 103 such that a profile of the outside projection 120 which is approximately trapezoidal in cross section is produced. It has to be understood that the face 120 b of the outside projection 120 that faces the first core part 103 and the face 120 c of the outside projection 120 that is remote from the first core part 103 can also be developed differently, in particular can be perpendicular on the longitudinal axis 153 or the main axis of the insertion portion 117, or however, can also be developed in the reverse trapezoidal manner such that an approximately dovetailed cross section of the outside projection 120 is formed. Finally, the projection can also comprise a rounded contour.

The receiving portion 118 of the second core part 104 comprises an inside projection 121 which is offset in relation to the position of the outside projection 120 in the direction of the first core part 103 and is directed radially in the direction of the longitudinal axis 153 of the armature 110 and has a completely closed ring-shaped development. The outside projection 120 and the inside projection 121 are arranged spaced apart from another in the longitudinal direction, the inside projection 121 comprising an inside ring surface 121 a which extends concentrically to the rest of the cylindrical shape of the insertion portion 117 and is connected to the inside ring surface 121 a by means of a face 121 b which faces the first core part 103, and which is connected to the receiving portion 118 by means of a second face 121 c which is remote from the first core part 103 and which faces the first face 120 b of the outside projection 120.

In the exemplary embodiment shown, the inside projection 121 and the outside projection 120 overlap in the projection in part such that when the coil 102 is excited and during the resultant stroke of the armature 110, the outside projection 120 moves closer to the inside projection 121. As a result, the force of the armature 110 is increased by the axial component produced in the region of the secondary air gap 152 such that the force acting on the armature 110 is increased in an end phase of the stroke of the armature 110. In an expedient manner, even at the maximum stroke of the armature 110 the inside projection 120 and the outside projection 121 are still spaced apart from one another such that there is never any contact.

It has to be understood that as an alternative to this, the outside projection 121 can also be arranged behind the inside projection 120 in the stroke direction of the actuator 110 when the coil 102 is excited such that the face 121 b that faces the first core part 103 then faces the face 120 c that is remote from the first core part 103. It is additionally possible for several inside projections 120 and/or several outside projections 121 to be provided, an inside projection and/or an outside projection then being able to be adjacent in each case to two surfaces of adjacent projections that face the same.

In an expedient manner, the inside projection 120 and the outside projection 121 can be realized such that they can be moved past one another such that the insertion portion 117 of the armature 110 is insertable into the receiving portion 118 of the second core part 104 from the direction of the first core part 103. According to an alternative development, it can be provided that at least one of the inside projection and outside projection is realized in an open manner such that the respectively other one is able to be moved past it.

The first exemplary embodiment operates in this case as follows:

A stronger magnetic axial force on the armature 110 and consequently a quicker stroke movement of the armature 110 in the direction of the first core part 103 is obtained as a result of the oppositely situated projections 120, 121 of the insertion portion 117 of the armature 110 and of the receiving portion 118 of the second core part 104. At the same time, a lesser magnetic force is obtained in an end region of the stroke path on account of, when looked at compared to a purely cylindrical contour of the insertion portion 117 and of the receiving portion 118, an increased magnetic resistance such that a weaker spring 111 is sufficient for the return movement of the armature 110.

FIG. 3 shows an alternative development of the secondary air gap, the same or structurally comparable parts of the electromagnetic pump comprising the same references as in the case of the exemplary embodiment according to FIGS. 1 and 2 and consequently only the differences being highlighted.

Whilst the design of the pump corresponds overall to that of the preceding exemplary embodiment, the insertion portion 217 of the armature 210 comprises an outside surface 222 which tapers in the conveying direction 112, the conical shape extending over almost the entire extension of the insertion portion 217. The cone angle, which is shown in FIG. 3, is chosen to be larger as would be case in practice for reasons of clarification. The receiving portion 218 comprises a hollow-cylindrical inside peripheral surface 223 such that when the coil 102 is de-excited, the size of the secondary air gap 252 between the insertion portion 217 and the receiving portion 218 is the minimum close to the end face of the receiving portion 218, and is the maximum close to the end of the receiving portion 218 that is remote from the first core part 103.

It has to be understood that in the same way a similar effect can be obtained when the receiving portion is conical and the insertion portion is cylindrical, or however when both the receiving portion and the insertion portion comprise a cone shape that is matched individually to one another.

The second exemplary embodiment operates in this case as follows:

Magnetic resistances other than in the case of a purely cylindrical form are produced in the rear region of the insertion portion 217 as a result of the chosen conical form of the insertion portion 217 such that a maximum magnetic force on the actuator 210 is already achieved at an earlier moment than in the case of an actuator with a cylindrical insertion portion.

The third exemplary embodiment according to FIG. 4 differs from the preceding exemplary embodiment only in the development of the insertion portion of the armature such that, for the rest, the same references as in the case of the preceding exemplary embodiment are used for the same or structurally comparable parts.

The armature 310 comprises an insertion portion 317 which is provided with a stepping 330 which is provided extending around the outside surface of the insertion portion 317 such that in an end face of the receiving portion 218 that faces the first core part 103 the secondary air gap 352 comprises a smaller size than in the rear region of the receiving portion 218 that is remote from the first core part 103. It has to be understood that the stepping 330 is also able to be arranged such that the recessed part is situated close to the front region 115 of the core part 310, and in addition it is also possible to provide more than one stepping, such as for example a cascade of small steppings over parts of the extension of the insertion portion 317 or over the entire insertion portion 317, in an expedient manner at least one quarter of the maximum extension of the secondary air gap 352 being realized differently from the remaining periphery of the insertion portion.

It has to be understood that combinations can also be obtained between the exemplary embodiment according to FIG. 3 and FIG. 4, for example conical portions which are separated from one another by steppings.

As a result of the chosen stepping, the magnetic resistance of the rear region of the insertion portion 317 differs from the front region of the insertion portion 317 which comprises a larger diameter such that a maximum magnetic force is influenced in a corresponding manner.

The fourth exemplary embodiment according to FIG. 5 differs from the second exemplary embodiment according to FIG. 3 only by the differently developed receiving portion such that the same or structurally comparable parts bear the same references as the exemplary embodiment according to FIG. 3.

In principle, the armature 210 shown in FIG. 5 is the same as that from FIG. 3, however the receiving part 418 is developed differently as a result of the inside peripheral surface 423 of the receiving portion 418 also comprising a conical form that is complementary to the conical form of the insertion portion 217, that means is realized as an inside cone that tapers in the conveying direction. As a result, when the coil 102 is de-excited, a secondary air gap 452 is produced with an almost constant size over the development of the insertion portion 217 such that a favorable magnetic resistance is produced as a result of the small secondary air gap 452. When the coil 102 is excited, the armature 210 is displaced, as a result of the axial movement of the armature 210 the size of the secondary air gap 452 increasing in proportion to the amount the armature 210 is displaced. As a result, the magnetic resistance is modified over the stroke path and in a corresponding manner influences the force with which the armature 210 is acted upon. To this is added that an axial component of the parts defining the secondary air gap 452 becomes effective as a result of the cone angle, which is shown in an exaggerated manner in the drawing but is noticeable, the effect of which on the force is disproportionately greater than the radial component.

FIG. 6 shows a further exemplary embodiment where the configuration of the secondary air gap is once again realized differently to in the case of the preceding exemplary embodiments, the same or structurally comparable parts having the same references as in the preceding exemplary embodiments.

The armature 510 comprises an insertion portion 517 which is realized in a rotationally symmetrical manner and the limiting curve of which comprises a constant, wave-shaped curved profile, having regions 517 a of larger diameter and regions 517 b of smaller diameter. The receiving portion 518 of the second core part 504 is defined by an envelope curve 523 which extends in a rotationally symmetrical manner and comprises regions of smaller inside diameter 523 a and regions of larger inside diameter 523 b. A secondary air gap 552, the size of which oscillates over the development, is produced as a result, when the coil 102 is excited even more modifications to the size of the secondary air gap 552 being induced, with the result of influencing the magnetic resistance in a corresponding manner.

It has to be understood that in an expedient manner the curve progressions 523, 517 are realized so as to be complementary to one another, and in this connection in an expedient manner the maximum outside diameter of the insertion portion 517 is smaller than the minimum inside diameter of the receiving portion 518, so that the second core part 504 is able to be realized in particular in one part and the armature 510 can be inserted into the second core part 504 from the direction of the first core part 103.

FIG. 7A to 7C show a schematic view of an electromagnetic pump 700, without showing a coil, other drive components, such as for example springs, or components for connection to a pump chamber 707.

An armature 710 is arranged in the pump chamber 707, which armature 710 is displaceable axially in the conveying direction. The pump chamber 707 is defined by components 703 which guide magnetic fields and, for example, correspond to the core parts 103, 104 and to the coil carrier 105 shown in the first exemplary embodiment, but are also able to assume other forms. In this case, a primary air gap is defined by a spacing between the armature 710 and a conical counterpart 719. In its front region 715 that faces the counterpart 719, the armature 710 comprises a truncated-cone-shape contour that tapers in the stroke direction. The conical counterpart 719, in this case, is realized on one of the components 703 that guide the magnetic field. In an end portion that is designated as an insertion portion 717 and is remote from the counterpart 719, the armature 710 comprises a ring-shaped outside projection 720 which extends from an end face of the armature 710 that is remote from the counter cone 719 over approximately one sixth of the insertion portion 717 and projects radially as far as approximately up to a center of the secondary air gap.

The components 703 include a receiving portion 718 in which the insertion portion 717 of the armature 710 is inserted. A radial inside projection 721, which projects approximately as far as up to a center of the secondary air gap, is arranged on the receiving portion such that the inside projection 721 and the outside projection 720 of the insertion portion 718 do not clash together when the armature 710 moves.

In FIG. 7A the outside projection 721 is arranged on a side of the inside projection 720 that is remote from the pump chamber 707. In this case, there is no radial overlap between the outside face of the outside projection and the inside face of the inside projection, which is designated in the present case as negative overlap. The position shown of the armature 710 is a non-excited stroke position, a coil (not shown) not being excited and the armature 710 being biased into the stroke position shown, for example by means of a spring. It has to be understood that a stop prevents the armature 710 from further movement in opposition to a bias.

FIG. 7B shows the armature 710 in a central stroke position, the inside face of the inside projection 721 being arranged opposite the outer face of the outside projection 720.

FIG. 7C shows the armature 710 in a deflected stroke position, the armature 710 being completely extended out of the receiving portion 718, and the front region 715 of the armature 710 being shown briefly before abutting against the counter cone 719. There is a negative overlap between the inside projection 721 and the outside projection 720 in this position too.

In the case of a negative overlap, the magnetic resistance of the entire arrangement is stronger than in the case of a positive overlap. In addition, the magnetic resistance is increased further when the armature 710 moves out of the receiving portion 718.

As a result, in the present seventh exemplary embodiment the behavior of the armature 710 is influenced to the extent that when the movement of the armature 710 is started, according to the state in FIG. 7A, a resistance present is approximately medium-sized such that a pressure peak, which would be produced in the pump chamber 707 if the coil were to be suddenly excited, is avoided. Whilst the outside projection 720 moves past the inside projection 721 as in FIG. 7B, the magnetic resistance drops and the maximum force of the pump can be used for conveying a fluid. In the position of the armature 710 shown in FIG. 7C, the magnetic resistance has strongly increased on account of the negative overlap as well as the position of the armature 710 outside the receiving portion 718 such that a hard knock against the counter cone 719 by the armature 710 is advantageously weakened.

Analogously to the exemplary embodiment shown in FIG. 7A-C, FIG. 8 shows a schematic view of a further exemplary embodiment of an electromagnetic pump 800 without showing a coil, other drive components, such as for example springs, or components for connection to a pump chamber 807. Identical or comparable components comprise a reference that has been incremented by 100 in relation to the exemplary embodiment of FIG. 7 such that a more detailed description of the position and character of the components is omitted below and only the differences are pointed out and described.

The pump 800 of the exemplary embodiment according to FIG. 8 is constructed as the pump 700 of the exemplary embodiment according to FIG. 7, an insertion region 817 of an armature 810 and a receiving portion 818 into which the armature 810 is inserted differing from the insertion portion 717 and the receiving portion 718 of the seventh exemplary embodiment. The outside diameter of the insertion portion 817 and the inside diameter of the receiving portion 818 comprise approximately the same size, a clearance, however, for the armature 10 to slide in the receiving portion 818 being provided. In a rear region that is remote from a counter cone 819, the insertion portion 817 comprises a groove 820 a, an outside projection 820 b being formed between an end face of the armature 810 that is remote from the counter cone 819 and the groove 820 a. The outside projection 820 b comprises an identical outside diameter as a remaining part of the insertion portion 817.

The receiving portion 818 also comprises a groove 821 a, an outside projection 820 b being formed between an end of the receiving portion 818 that faces the counter cone 819 and the groove 820 a. The outside projection 820 b comprises an identical outside diameter as a remaining part 817 a of the insertion diameter 817.

FIG. 8 shows the armature 810 in a central stroke position, the inside face of the inside projection 821 b being arranged opposite the outer face of the outside projection 820 b.

In contrast to the pump 700 of the seventh exemplary embodiment, a negative overlap between the insertion portion 817 and the receiving portion 818 is not produced at the start of a movement of the armature 810 such that there is no reduction in the magnetic resistance. As a result, the armature 810 is advantageously accelerated in a quicker manner, which advantageously leads to a reduced operating time of the coil and consequently to a lower current consumption.

FIG. 9 shows an electromagnetic pump 900 that is realized as a dosing pump, having a housing 901, an electromagnetic coil 902 that is arranged in the housing 901, a first ferromagnetic core part 903 and a second ferromagnetic core part 904. The electromagnetic coil 902 is wound on a coil carrier 905 and in its inside region is penetrated in each in case in part by the first ferromagnetic core part 903 and the second ferromagnetic core part 904. The two ferromagnetic core parts 903, 904 are spaced apart from one another by a pump chamber 907 which defines a spacing 906, the first ferromagnetic core part 903 comprising a feed line 908 and the second ferromagnetic core part 904 comprising an outlet line 909 for a fluid to be conveyed. A movable, ferromagnetic armature 910 is arranged in the pump chamber 907, which armature 910 is biased into a conveying direction 912 of the electromagnetic pump 900 by means of a spring 911 which is arranged between the armature 910 and the first core part 903. The armature 910 comprises a substantially hollow-cylindrical form and is penetrated by a piston rod 913 in its entire longitudinal extension, the piston rod 913 projecting beyond the armature 110 in the conveying direction 912 by way of one end 913 a and abutting against the outlet line 909 and closing the same when the coil 902 is totally de-excited. The armature 910 comprises in its front region 915 which faces the first core part 903 a truncated-cone-shaped contour that tapers in the stroke direction. The first core part 903 comprises a conical counterpart 919 which faces the armature 910 and is realized in a complementary manner to the front region 915 of the armature 910, a region between the armature 910 and the conical armature counterpart 919 being designated as a primary air gap. The front region 915 projects into the axial spacing between both core parts 903, 904. The armature 910 extends by way of an end, which is remote from the first core part 903 and is realized as an insertion portion 917, into a receiving portion 818 of the second core part 904, the front region 915 of the armature 910 not protruding radially beyond an end face of the receiving portion 918 of the second core part 904 that faces the first core part 903, as a result of which core parts 903, 904 with a smaller diameter are also able to be used. It is, however, possible to allow the front region 915 of the armature 910 also to protrude radially beyond the end face of the receiving portion 918 that faces the first core part 903.

A region between the insertion portion 917 of the armature 910 and the receiving portion 918 of the second core part 904 is designated as a secondary air gap. The region between the front region 915 of the armature 910 and the counterpart 919 of the first core part 903 defines a primary air gap 951, the axial extension of which is the maximum when the coil 902 is de-excited. The peripheral surface of the insertion portion 917 of the armature 910 and the receiving portion 918 of the second core part 904 that faces the longitudinal axis 953 of the coil 902 define a substantially radial secondary air gap 952 in the region in which they are situated opposite one another.

When the coil 902 is excited, on account of the magnetic field produced, the magnetic force between the armature 910 and the first core part 903 during a closing operation of the first air gap 951 is greater than the magnetic force between the armature 910 and the second core part 904.

When the coil 902 is excited, a magnetic field is generated inside the coil 902, the ferromagnetic armature 910 being acted upon in opposition to the conveying direction 912 by a magnetic force and being displaced. The magnetic force moves the armature 910 in the direction of the first core part 903 in opposition to the bias of the spring 911, the front region 915 of the armature 910 being pushed into the complementarily realized counterpart 919 of the first core part 903. The spring 911 is tensioned further at the same time. When the coil 902 is de-excited, the armature 910 is once again displaced in the conveying direction 912 as a result of the bias of the spring 911, and the end 913 a of the piston rod 913 presses the fluid into the outlet line 909.

A conical portion 960 of the insertion portion 917 of the armature 910 tapers in opposition to the truncated-cone-shaped contour of the front region 915 of the armature 910 that tapers in the stroke direction, proceeding from an end face 961 of the insertion portion 917. A cylindrical region 962 of the insertion portion 917, which reaches as far as up to an end wall 963 of the insertion portion 917 in which the outlet line 909 opens out in an indentation 964 which is larger than the end 913 a of the piston rod 913, connects to the single conical portion 960 that points only in one direction.

A conical portion 970 of the insertion portion 917 of the armature 910 extends in part in radial overlap with the conical portion 960 of the insertion portion 917, in part outside the receiving portion 918, in the non-excited end position of the armature 910 shown in FIG. 9. At maximum stroke, the conical portion 970 of the insertion portion 917 of the armature 910 passes fully outside radial overlap with the conical portion 960 of the insertion portion 917. A continuously cylindrical region 971 of the armature 910, which, in the non-excited state, is surrounded radially in part by the conical portion 960 of the insertion portion 917, connects to the conical portion 970 of the insertion portion 917 in the conveying direction.

A cylindrical portion 972, to which, in turn, connects the truncated-cone-shaped contour of the front region 915 of the armature 910, which tapers in the stroke direction and is defined by a ring-shaped end face 973 of the armature 910 that faces the first core part 903, connects to the conical portion 970 of the insertion portion 917 in the stroke direction. It is recognized that the conical portion 970 makes up more than one sixth of the axial extension of the insertion portion 917 which reaches from an end face 974 of the armature 910 that faces the outlet line 909 as far as up to the cylindrical portion 972, however without said portion. It is additionally recognized that the conical portion 960 also makes up somewhat more than one sixth of the axial extension of the receiving portion 916.

It is further recognized that the conical portion 970 of the insertion portion 917 that tapers in opposition to the stroke direction is steeper than the truncated-cone-shaped contour of the front region 915 of the armature 910 that tapers in the stroke direction as a longer axial spacing is available to the front region 915 for approximately the same radial spacing. It is further recognized that the cone angle of the conical portions 970 and 960 is approximately the same and differs by less than 8°. The cone angle of the front region 915 of the armature 910 and of the counterpart 919 is approximately the same and differs by less than 8°.

A non-return valve 980, which is biased by means of a spring 981 in the closing direction that corresponds to the stroke direction of the armature 910, is arranged in the feed line 908. A sleeve 982, the bore 983 of which is partially penetrated by the piston rod 913, is arranged in the bore 903 a of the first core part that is enlarged in relation to the feed line 908. A suction chamber 984, which is radially surrounded by the sleeve 982 between the valve member of the non-return valve 980 and the end face of the piston rod 913 that faces the feed line 908, is connected to the pump chamber 907, for example by means of a bore that includes a valve in the piston rod 913 which is not shown in any more detail. If the coil 902 is excited, the non-return valve 980 prevents the fluid from escaping, and said fluid is pressed by means of the connection in the pump chamber 907. If the armature 910 is displaced back into its starting position by the spring 911, a negative pressure, which raises the valve member of the non-return valve 980 and allows the fluid to flow, is generated in the suction chamber 984, whilst the fluid is pressed out of the pump chamber 907 into the outlet line 909 when the armature 910 is reset. It is recognized that the spring 911 is supported on an end face of the sleeve 982. It is additionally recognized that the bores in both core parts 903, 904 comprise a continuous bore which has a diameter which increases in steps from out to in such that simple mounting is possible by inserting components such as the sleeve 982 or the non-return valve 980.

It is further recognized that two pole disks 991, 992, which promote the magnetic flux to the coil 902 in the manner of a yoke, are introduced in the housing 901.

The form features on the armature 910 that are shown in FIG. 9 and are explained above, in particular the arrangement, length and angle of the conical portion 970 of the insertion portion 917, which can also be designated as a secondary cone, and on the conical counterpart 919, in particular the length, diameter and angle, produce additional degrees of freedom for optimizing the force progression as a function of the stroke. A sufficient acceleration at the start of the stroke, a force that increases with the stroke to overcome the bias of the spring 911 as well as a moderate and at all times not too great an excess of force at the end of the movement of the armature 910 are achieved consequently among other things in the present realization. As a result, the armature 910 reaches and securely holds the end of the stroke, but only hits the conical counterpart 919 with a small excess of force, even in the case of variable supply voltage and changing coil temperature. As a result, oscillations and temperature rises introduced unnecessarily into the dosing pump 900 are avoided, which leads to an extended service life.

It has to be understood that the exemplary embodiments shown or the elements thereof are easily able to be combined, aggregated, substituted or modified to achieve the success according to the invention.

The invention has been explained above with reference to primary and secondary air gaps. It has to be understood that the air gaps in the operation of the electromagnetic pump can be filled not with air but with the medium to be conveyed, pump oil or another medium, and can also include, in particular, the sleeve that promotes reciprocal guiding, for example produced from Teflon or the like.

The invention has been described above by way of a development of the electromagnetic pump as an injection pump with a dosing cylinder. It has to be understood that an armature that acts as a piston can also be used instead of a dosing cylinder, or that the pump can also be realized as a diaphragm pump where the fluid to be conveyed remains outside the air gaps.

The invention has been explained above by way of exemplary embodiments where, as a result of exciting the coil, the actuator is raised in opposition to the conveying direction of the fluid, and the fluid to be conveyed is ejected under the bias of the spring. It has to be understood that the invention is able to be realized in the same way with a pump where the ejection of the liquid is effected as a result of the stroke of the armature when the coil is excited, and simply the return is provided under the bias of the spring.

The invention has been explained by way of exemplary embodiments where specific contours of the insertion portion and of the receiving portion have been described. It has to be understood that any adaptation to a desired stroke-force characteristic is able to be achieved as a result of a configuration according to the invention in the region of the secondary air gap.

The invention has been described above by way of exemplary embodiments where the insertion portion and the receiving portion are realized as integral parts. It has to be understood that from a manufacturing point of view said parts are able to be assembled from several parts, for example from a basic part with a cylindrical contour and a bushing part which is shrunk or pressed on and is ferromagnetic at least in part and accordingly comprises a specific ferromagnetic contour. It is possible, in particular, by means of a corresponding bushing to assemble a modular range where the characteristic in the region of the secondary air gap is influenced as a result of the type of usual lining or bushing. As a result of a corresponding development of the lining or of the bushing, it is also possible to distribute the ferromagnetic characteristics in a non-rotationally symmetrical manner over the periphery of the insertion portion or the receiving portion and, as a result, to achieve further magnetic effects in the region of the secondary air gap. 

1. An electromagnetic pump, comprising precisely one coil, wherein the one coil comprises a longitudinal axis, a ferromagnetic first core part which is arranged at least in part in the one coil, a ferromagnetic second core part which is arranged at least in part in the one coil, and a ferromagnetic armature, wherein a primary air gap is arranged between the armature and the first core part, wherein a secondary air gap is radially arranged between an insertion portion of the armature and a receiving portion of the second core part that is turned to the longitudinal axis, wherein the ferromagnetic armature comprises a truncated-cone-shaped contour which tapers in a stroke direction in a front region which faces the first core part, wherein during a closing operation of the first air gap, a magnetic force between the armature and the first core part is greater than a magnetic force between the armature and the second core part, and wherein the insertion portion of the armature comprises at least one conical portion which comprises an opening angle which deviates from the truncated-cone-shaped contour of the front region of the ferromagnetic armature.
 2. The electromagnetic pump as claimed in claim 1, wherein at least one of the insertion portion of the armature and the receiving portion of the second core part comprises a contour which deviates from the cylindrical contour over a region of at least one sixth of a maximum axial extension of the secondary air gap.
 3. The electromagnetic pump as claimed in claim 1, wherein at least one of the insertion portion of the armature and the receiving portion of the second core part is realized in a conical manner over a region of at least one sixth of a maximum axial extension of the secondary air gap.
 4. The electromagnetic pump as claimed in claim 1, wherein the insertion portion of the armature comprises a stepping with a widened secondary air gap.
 5. The electromagnetic pump as claimed in claim 1, wherein the receiving portion of the second core part comprises an inside projection which points to the longitudinal axis.
 6. The electromagnetic pump as claimed in claim 1, wherein, in a region of the secondary air gap, a maximum outside diameter of the insertion portion of the armature is smaller than a minimum inside diameter of the receiving portion of the second core part.
 7. The electromagnetic pump as claimed in claim 1, wherein the front region of the armature protrudes radially beyond an end face of the receiving portion of the second core part that faces the first core part.
 8. The electromagnetic pump as claimed in claim 1, wherein the conical portion of the insertion portion of the armature tapers in opposition to a truncated-cone-shaped contour of the front region of the armature which tapers in the stroke direction.
 9. The electromagnetic pump as claimed in claim 8, wherein the conical portion of the insertion portion of the armature extends in part outside the receiving portion.
 10. The electromagnetic pump as claimed in claim 1, wherein the conical portion of the receiving portion which tapers in opposition to the stroke direction adjoins an end face of the second core part that faces the first core part.
 11. The electromagnetic pump as claimed in claim 1, wherein the conical portion of the insertion portion which tapers in opposition to the stroke direction is steeper than the truncated-cone-shaped contour of the front region of the armature which tapers in the stroke direction.
 12. The electromagnetic pump as claimed in claim 1, wherein a region of the receiving portion, which is placed outside the conical portion of the receiving portion that tapers in opposition to the stroke direction and points in a pumping direction is realized in a cylindrical manner, and wherein a region of the insertion portion which penetrates into the cylinder region of the receiving portion is realized in a cylindrical manner.
 13. The electromagnetic pump as claimed in claim 1, wherein the armature assumes its maximum diameter in a space that is surrounded by the coil outside the receiving portion of the second core part and outside the first core part.
 14. The electromagnetic pump as claimed in claim 1, wherein an effective piston area of the armature which points in a pumping direction is greater than an effective piston area of the armature that points in the stroke direction.
 15. The electromagnetic pump as claimed in claim 1, wherein the pump is selected from the group comprising a reciprocating pump, a diaphragm pump, a pressure-regulating pump and a dosing pump. 